1. Field of the Invention
The invention relates to a brake control system which controls braking force applied to a wheel provided on a vehicle.
2. Description of the Related Art
Japanese Patent Application Publication No. JP-A-2005-41319, for example, describes a known braking force control system which calculates a target deceleration based on a hydraulic pressure in a master cylinder and a pedal stroke of a brake pedal, and controls the braking force so that the target deceleration is applied to the vehicle. In this braking force control system, the target deceleration is calculated to be larger the greater the master cylinder pressure or the larger the pedal stroke. Also, a stroke simulator which creates a reaction force with respect to an operation of the brake pedal by a driver is connected to the master cylinder.
In the foregoing braking force control system, when the driver depresses the brake pedal, the hydraulic pressure in the master cylinder increases in response to the depression force and operating fluid flows out from the master cylinder to the stroke simulator. The transient response of the master cylinder pressure at this time differs depending on the speed or rate at which the brake pedal is depressed. That is, when the brake is operated suddenly, the master cylinder pressure first becomes relatively high and then drops to an equilibrium master cylinder pressure as operating fluid flows out to the stroke simulator. When the brake is operated slowly, on the other hand, the master cylinder pressure approaches the equilibrium master cylinder pressure without becoming all that high.
As a result, the master cylinder pressure immediately after the brake operating member is operated tends to become larger the more sudden an operation of the brake operating member and the faster the speed of that operation. Therefore, as the speed at which the brake operating member is operated increases the target deceleration does so, as well. As a result, the speed at which the brake operating member is operated ends up affecting the brake feeling in such a way that the braking effect is keenly felt by the driver.